U.S. patent application number 10/547640 was filed with the patent office on 2006-07-27 for high-speed digital video camera system and controller therefor.
Invention is credited to Timothy Nicholas Dammery, Nicki John Paris, Christopher Paul Robinson.
Application Number | 20060164534 10/547640 |
Document ID | / |
Family ID | 9953999 |
Filed Date | 2006-07-27 |
United States Patent
Application |
20060164534 |
Kind Code |
A1 |
Robinson; Christopher Paul ;
et al. |
July 27, 2006 |
High-speed digital video camera system and controller therefor
Abstract
A high-speed digital video camera (3) and controller display
unit (CDU) (5) therefor are disclosed. The CDU (5) comprises a
display screen (50) and a control console having one or more
control elements (54, 56). The CDU (5) is adapted to be connected
to the camera (3) by means of a controller display interface (32)
of the camera (3), and to display video images received from the
camera without storing video image data locally to the CDU. The
images are preferably displayed substantially immediately by the
CDU (5). The camera (3) contains the main image processing
hardware, so that the CDU (5) may be highly portable and easily
connected to the camera for immediate use. A high-speed digital
video camera system (1) and a method of controlling the same are
also disclosed.
Inventors: |
Robinson; Christopher Paul;
(Basildon, GB) ; Dammery; Timothy Nicholas;
(Leigh-on-Sea, GB) ; Paris; Nicki John; (Essex,
GB) |
Correspondence
Address: |
Smith Gambrell & Russell
1850 M Street N W
Suite 800
Washington
DC
20036
US
|
Family ID: |
9953999 |
Appl. No.: |
10/547640 |
Filed: |
February 27, 2004 |
PCT Filed: |
February 27, 2004 |
PCT NO: |
PCT/GB04/00796 |
371 Date: |
September 1, 2005 |
Current U.S.
Class: |
348/333.01 ;
348/E5.042; 348/E5.047; 348/E5.091 |
Current CPC
Class: |
H04N 5/335 20130101;
H04N 5/23206 20130101; H04N 5/225251 20180801; H04N 5/232935
20180801 |
Class at
Publication: |
348/333.01 |
International
Class: |
H04N 5/222 20060101
H04N005/222 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2003 |
GB |
0304804.8 |
Claims
1. A controller display unit (CDU) for a high-speed digital video
camera, comprising: a display screen; and a control console having
one or more control elements, wherein the CDU is adapted to be
connected to a high-speed digital video camera and to display video
images received from the camera without storing video image data
locally to that CDU.
2. The CDU of claim 1, further adapted to receive video image data
such that the video images are substantially immediately displayed
by the CDU.
3. The CDU of claim 1, further adapted to receive and display
graphical overlay data, the data being indicative of one or more
functions of the camera.
4. The CDU of claim 1, further adapted to transmit a control signal
to the camera in response to a user operation of one of the control
elements.
5. The CDU of claim 4, wherein the control signal is representative
of the control element operated.
6. The CDU of claim 4, further comprising a CDU microprocessor
adapted to convert the user operation of one of the control
elements into a serial control signal for transmission to the
camera microprocessor.
7. The CDU of claim 6, wherein the control signal is a RS-232
signal.
8. The CDU of claim 1, wherein the video image data received by the
CDU are in a low-voltage differential signalling (LVDS) form and
the CDU further comprises a LVDS receiver chip interfacing with the
display screen.
9. The CDU of claim 1, wherein the CDU is hand-held.
10. The CDU of claim 1, wherein the CDU has at least one of: a
flip-out stand, an adjustable hand-strap, and a tripod mounting
thread.
11. The CDU of claim 1, wherein the CDU is adapted to be connected
to the camera by means of a single cable interface, the cable being
adapted to carry signals in both directions and to carry power from
the camera to the CDU.
12. A high-speed digital video camera, comprising: an image sensor,
adapted to detect an image to be viewed and recorded; a video
memory within the camera, adapted to store at least temporarily
image data derived from the image sensor; a camera microprocessor
within the camera, adapted to process data received in the camera;
and a controller display interface, adapted to be connected to a
controller display unit (CDU) and to transmit video image data to
the CDU for display by the CDU without storing the video image data
locally to that CDU.
13. The camera of claim 12, wherein the camera is adapted to
transmit video image data to the CDU such that video images are
substantially immediately displayed by the CDU.
14. The camera of claim 12, wherein the camera is further adapted
to transmit graphical overlay data to the CDU, the data being
indicative of one or more functions of the camera.
15. The camera of claim 12, wherein the controller display
interface is further adapted to receive control signals from the
CDU.
16. The camera of claim 15, wherein the camera microprocessor is
adapted to interpret the control signals to determine the one or
more functions to be performed by the camera.
17. The camera of claim 12, further comprising a feature connector
interface, adapted to be connected to a trigger device and to
receive trigger signals for controlling a start or stop of a camera
record function.
18. The camera of claim 12, further comprising a computer
interface, adapted to be connected to a computer and to transmit
the video image data to the computer for downloading, playing back
and saving by the computer.
19. The camera of claim 18, wherein the computer interface is
further adapted to receive control signals from the computer.
20. The camera of claim 17, wherein the camera is adapted to
interpret signals received through each of the respective
interfaces differently and, where requested, to return data to the
appropriate interface.
21. The camera of claim 17, wherein the feature connector interface
is further adapted to be connected simultaneously to a plurality of
devices and to receive one or more of a trigger signal, an analogue
signal, and a camera timing synchronization signal, and to transmit
one or more of a video image signal and a camera timing
synchronization signal.
22. The camera of claim 12, wherein the camera microprocessor
includes a clock having a clock frequency, and wherein the
controller display interface has a bus width, each of which
provides a video image data transfer rate of the camera which is
matched to a video image display rate upon the CDU.
23. The camera of claim 12, further comprising a PCMCIA slot, for
saving selected video image data to a removable memory.
24. A high-speed digital video camera system, comprising: i) a
high-speed digital video camera, comprising: an image sensor,
adapted to detect an image to be viewed and recorded; a video
memory within the camera, adapted to store at least temporarily
image data derived from the image sensor; a camera microprocessor
within the camera, adapted to process data received in the camera;
and a controller display interface; and ii) a CDU, comprising: a
display screen; and a control console having one or more control
elements, wherein the CDU is connected to the controller display
interface of the camera, the camera being adapted to transmit video
image data to the CDU and the CDU being adapted to display video
images received from the camera without storing the video image
data locally to that CDU.
25.-33. (canceled)
34. A method of controlling a high-speed digital video camera
system, comprising: i) a high-speed digital video camera,
comprising: an image sensor, adapted to detect an image to be
viewed and recorded; a video memory within the camera, adapted to
store at least temporarily image data derived from the image
sensor; a camera microprocessor within the camera, adapted to
process data received in the camera; and a controller display
interface; and ii) a CDU, comprising: a display screen; and a
control console having one or more control elements, the method
comprising the steps of: a) transmitting video image data from the
camera to the CDU; and b) displaying on the display screen video
images received from the camera by the CDU without storing the
video image data locally to that CDU.
35. The method of claim 34, wherein the camera transmits video
image data, and the CDU receives the video image data, such that
the video images are substantially immediately displayed by the
CDU.
36. The method of claim 34, further comprising the step of: c)
generating and transmitting to the CDU from the camera graphical
overlay data, and displaying on the display screen a graphical
overlay indicative of one or more functions of the camera.
37. The method of claim 36, further comprising the step of: d)
selecting from the one or more functions represented by the
graphical overlay a desired function and operating a corresponding
control element.
38. The method of claim 37, further comprising the step of: e)
converting the operation of the control element into a control
signal representative of the control element operated and
transmitting the control signal to the camera microprocessor.
39. The method of claim 38, further comprising the step of: f)
processing the control signal received from the CDU and returning
to step (a), with the video image data and/or the graphical overlay
data transmitted to the CDU being changed by the camera as
required.
40. The method of claim 34, wherein, in use, the camera is
controlled solely with the CDU.
41. The method of claim 34, wherein the video image data are
carried as a serial data stream in the form of low-voltage
differential signalling (LVDS).
42. The method of claim 34, wherein a video image data transfer
rate of the camera to the CDU corresponds to a video image display
rate of the CDU.
43. The method of claim 36, wherein the one or more functions of
the camera include one or more of: i) setting a parameter value of
the camera, such as frame speed, shutter speed, camera focus, or
frame size; and ii) starting or stopping a camera operation, such
as live image feeding, recording, playing back, bookmarking, clip
selecting, or saving.
44. The method of claim 43, wherein a start or stop signal of the
camera record function is received as a trigger signal from either
a CDU control element operation, a trigger device, or a second
camera connected to the camera, the second camera generating and
transmitting to the camera a trigger signal when the second camera
has reached a pre-defined stage in recording.
Description
[0001] The present invention relates to a high-speed digital video
camera system. The invention also extends to a controller for use
in such a system.
[0002] High-speed digital video cameras are well known in industry
for their use in analysing events or processes which the human eye,
or a conventional video camera, is unable to capture with
sufficient detail. The range of uses of high-speed video cameras
extends to the fields of combustion and detonation events, robotic
operations, high-speed mechanical operations timing analysis,
ballistics testing, swing analysis in sports such as tennis or
golf, liquid and gas flow investigations, and vehicle impact
testing.
[0003] High-speed digital video cameras usually employ a CCD
(charge-coupled device) or a CMOS image sensor array, with
full-frame resolutions extending into the megapixel range. The
frame rate of such cameras may usually be set at between 20 fps
(frames per second) and 1,000 fps for full-frame imaging and up to
10,000 fps or more for partial-frame imaging. The recorded camera
images are normally stored in DRAM, rather than on moving film or
tape, due to the inherent speed constraints of moving mechanical
parts. This memory tends to be the limiting factor in determining
the maximum recording time of a camera system. A camera therefore
needs to be configured appropriately, in order to maximise the
recording time and recorded image quality, as required by any
particular desired application.
[0004] As will be appreciated, in order to configure a high-speed
digital video camera for any particular scene to be recorded, there
is a large number of variables which need to be set. These include,
among others, the frame rate, frame size, shutter speed, and camera
focus. In addition, the recorded image playback and saving
functions of a camera system both require further operator
controls.
[0005] Prior art high-speed digital video camera systems have taken
a number of approaches to controlling the operation of the
camera.
[0006] A first system, such as the SpeedCam or the SpeedCam Pro
(manufactured by Weinberger GmbH), employs a control box which is
connected by a cable to a remote camera head. The control box
contains all of the processing electronics of the camera system.
That is, the control box contains hardware such as a PC circuit
board and a PCI card containing the camera electronics. The control
box may also include a monitor, or this may be provided separately.
The camera head of such systems is usually relatively small.
However, the control box, incorporating the PC hardware, camera
electronics and monitor, tends to be rather bulky and usually
requires further interfaces, such as a keyboard and a mouse.
[0007] A second system, known as a PCI camera, consists of a remote
camera head, connected by a cable to a PCI card containing the
camera electronics. One such camera is the MotionScope PCI camera
(manufactured by Redlake MASD, Inc.). A separate PC, or laptop, is
required to operate the camera, by connecting the PCI card to the
printed circuit board of the computer. In addition, the computer
requires custom software, which enables it to display the video
image in a window on the computer monitor and to control the camera
in response to user instructions. Again, such a system requires the
use of a bulky PC or laptop and may additionally need a keyboard
and mouse. Furthermore, the user must fit the PCI card to the
computer before use and is then limited to use of the camera only
with that computer and with the appropriate software installed.
[0008] A third high-speed video camera system, known as an
all-in-one or self-contained camera is such that the camera
electronics, along with the imaging hardware of the camera, are
contained within the camera itself. This approach is used in the
Phantom camera series (manufactured by Vision Research, Inc.). A
high-speed interface, such as FireWire, is used to connect the
camera to a PC or laptop, which then displays the image and
controls the camera. The computer in this system, using suitable
software, performs all of the calculations and control decisions of
the system and then sends appropriate commands to the camera. This
system therefore requires the use of a bulky computer and other
peripheral devices mentioned above. In addition, the computer of
this system does not display real-time video footage, since the
video data is transmitted asynchronously from the camera to the
computer, in small data packets. This results in the timing of the
image display being uncertain, depending on the size and speed of
transmission of the individual video data packets.
[0009] Another type of all-in-one camera has a high-speed video
memory and a microprocessor built in to the camera itself. One such
camera (manufactured by Redlake MASD, Inc.) may be connected to a
remote control, consisting of push button switches and LEDs
(light-emitting diodes). This may be used to control some of the
camera functions, but a TV monitor, PC or laptop is still required
to enable image viewing.
[0010] Another all-in-one camera (manufactured by Weinberger GmbH),
also has a remote control for camera operation, but its use is tied
to dedicated switches on the camera itself. This means that only
partial functionality of the camera may be controlled remotely,
since some of the camera functions may be accessed only by means of
the camera itself. It is often undesirable to approach a camera
during or after imaging, because of the operating conditions in
some applications.
[0011] Two further all-in-one cameras, the MotionXtra HG100K and
MotionXtra CR2000 (manufactured by Redlake MASD, Inc.), also
include remote controls. The HG100K has an optional tablet style
display control unit, to enable set-up of remotely located cameras.
The CR2000 has a handheld keypad, similar to a PDA (personal
digital assistant), which provides access to some, but not all, of
the features of the system. However, in order to obtain
full-feature video with these units, they must either be connected
to a PC, as above, or the data must be first written to a memory
card and then viewed via a PC.
[0012] The problem with the above camera systems is that, in order
to provide a fully functioning high-speed digital video camera
system, they each require the use of numerous devices in addition
to the camera itself. This results in complex, often bulky
arrangements, for which many cables (for both powering and
connecting the devices) are needed. For many applications, this is
highly undesirable, in terms of the time taken to configure such
systems (including the switch-on time for a PC), the low
portability of these systems, and the requirement for many power
points for the devices. There is a great number of uses for
high-speed digital video cameras and many of these applications
would benefit from fast and easy set-up and high portability of the
camera system, with the capacity for real-time viewing and
immediate, easily visible video playback.
[0013] The present invention aims to address the above objectives
by providing an improved high-speed digital video camera system and
method for controlling the system.
[0014] According to a first aspect of the present invention, there
is provided a controller display unit (CDU) for a high-speed
digital video camera, comprising a display screen and a control
console having one or more control elements, wherein the CDU is
adapted to be connected to a high-speed digital video camera and to
display video images received from the camera without storing video
image data locally to that CDU.
[0015] Providing a unit on which video images may be displayed
without the need to store video image data in the unit offers the
advantage of so-called real time viewing of a scene being imaged by
a high-speed video camera and playback of recorded video footage.
This also greatly simplifies the electronics required in the CDU,
since no data storage and very little processing hardware is
required. The high-speed video camera intended for use with the CDU
contains all of the main image processing hardware, which means
that the CDU is highly portable and easily connected to such a
camera for immediate use.
[0016] Preferably, video image data are received by the CDU such
that the video images are substantially immediately displayed by
the CDU. This allows a user to take high-speed video footage almost
anywhere and to review the footage immediately, in order to be able
to select clips which are to be saved.
[0017] In a preferred embodiment, the CDU is adapted to receive and
display graphical overlay data, the data being indicative of one or
more functions of the camera. Alternatively or additionally, the
CDU is adapted to transmit a control signal to the camera in
response to a user operation of one of the control elements.
Preferably, the control signal is representative of the control
element operated. This has the advantage of enabling a user to
observe the effect of his control actions instantly, thereby
enhancing user-friendliness. The on-screen display of available
options also facilitates understanding of a camera's performance
parameters. The use of control signals which indicate the control
key operated, rather than a specific, dedicated function to be
performed, offers the advantage of easy navigation through a camera
menu and fast operation of the CDU interface.
[0018] Preferably, the video image data received by the CDU are in
a low-voltage differential signalling (LVDS) form and the CDU
further comprises a LVDS receiver chip interfacing with the display
screen. This offers high-speed, serial digital data transfer to the
CDU, for an optimum display rate.
[0019] In a preferred embodiment, the CDU is adapted to be
connected to a camera by means of a single cable interface, the
cable being adapted to carry signals in both directions and to
carry power from the camera to the CDU. This advantageously reduces
the number of cables required for operation of the CDU with a
camera, reducing set-up time, the number of power supply points
needed and obstacles, which may hinder filming and user
accessibility.
[0020] According to a second aspect of the present invention, there
is provided a high-speed digital video camera, comprising an image
sensor, adapted to detect an image to be viewed and recorded; a
video memory within the camera, adapted to store at least
temporarily image data derived from the image sensor; a camera
microprocessor within the camera, adapted to process data received
in the camera; and a controller display interface, adapted to be
connected to a controller display unit (CDU) and to transmit video
image data to the CDU for display by the CDU without storing the
video image data locally to that CDU.
[0021] In a preferred embodiment, the camera further comprises a
feature connector interface, adapted to be connected to a trigger
device and to receive trigger signals for controlling a start or
stop of a camera record function. Additionally or alternatively,
the camera may comprise a computer interface, adapted to be
connected to a computer and to transmit the video image data to the
computer for downloading, playing back and saving by the computer,
or receiving control signals from the computer. Preferably, the
camera is adapted to interpret signals received through each of the
respective interfaces differently and, where requested, to return
data to the appropriate interface. Preferably, the feature
connector interface is further adapted to be connected
simultaneously to a plurality of devices and to receive one or more
of a trigger signal, an analogue signal, and a camera timing
synchronization signal, and to transmit one or more of a video
image signal and a camera timing synchronization signal. This
advantageously offers a highly multi-functional camera, which may
be used in many different modes. The choice of user interface
affords a user great flexibility in the precise set-up of the
camera, which may vary greatly according to the desired application
of the camera.
[0022] Preferably, the camera has a PCMCIA slot, for saving
selected video image data to a removable memory. This allows more
video footage than can be stored in the camera alone to be saved,
without the need to download to a bulky computer.
[0023] According to a third aspect of the present invention, there
is provided a high-speed digital video camera system, comprising i)
a high-speed digital video camera, comprising an image sensor,
adapted to detect an image to be viewed and recorded; a video
memory within the camera, adapted to store at least temporarily
image data derived from the image sensor; a camera microprocessor
within the camera, adapted to process data received in the camera;
and a controller display interface; and ii) a CDU, comprising a
display screen; and a control console having one or more control
elements, wherein the CDU is connected to the controller display
interface of the camera, the camera being adapted to transmit video
image data to the CDU and the CDU being adapted to display video
images received from the camera without storing the video image
data locally to that CDU.
[0024] According to a fourth aspect of the present invention; there
is provided a method of controlling a high-speed digital video
camera system, comprising i) a high-speed digital video camera,
comprising an image sensor, adapted to detect an image to be viewed
and recorded; a video memory within the camera, adapted to store at
least temporarily image data derived from the image sensor; a
camera microprocessor within the camera, adapted to process data
received in the camera; and a controller display interface; and ii)
a CDU, comprising a display screen; and a control console having
one or more control elements, the method comprising the steps of a)
transmitting video image data from the camera to the CDU; and b)
displaying on the display screen video images received from the
camera by the CDU without storing the video image data locally to
that CDU.
[0025] Preferably, the camera is controlled solely with the CDU.
This advantageously provides a highly portable system, which is
simple to use and does not require extra peripheral devices or
cables.
[0026] Preferably, a start or stop signal of the camera record
function is received as a trigger signal from either a CDU control
element operation, a trigger device, or a second camera connected
to the camera, the second camera generating and transmitting to the
camera a trigger signal when the second camera has reached a
pre-defined stage in recording. This provides the option of
daisy-chaining high-speed video cameras together, so that once one
camera has filled its memory capacity, the next camera begins to
record and so on. Alternatively, a scene may be recorded in
synchronization from many different angles and locations.
[0027] Other preferred features are set out in the dependent claims
which are appended hereto.
[0028] The present invention may be put into practice in a number
of ways and some embodiments will now be described, by way of
example only, with reference to the following figures, in
which:
[0029] FIG. 1 shows a schematic representation of a high-speed
digital video camera system embodying the present invention,
including a high-speed digital video camera and a controller
display unit (CDU);
[0030] FIG. 2 shows a rear and side view of the camera of FIG.
1;
[0031] FIG. 3 shows a schematic block circuit diagram of the
high-speed digital video camera of FIG. 2;
[0032] FIG. 4A shows a front view of the CDU of FIG. 1;
[0033] FIG. 4B shows a rear view of the CDU of FIG. 1;
[0034] FIG. 5 shows a schematic block circuit diagram of the CDU of
FIGS. 4A and 4B; and
[0035] FIGS. 6A and 6B show, in black and white, exemplary display
screen outputs of the CDU of FIGS. 4A and 4B.
[0036] FIG. 1 illustrates an embodiment of a high-speed digital
video camera system 1 of the present invention. The system 1
includes at least a high-speed digital video camera 3 (hereinafter
referred to simply as a camera 3) and a controller display unit
(CDU) 5. FIG. 1 also shows a trigger switch 7, connected to the
camera 3 by a feature connector cable 8. The camera 3 is powered by
a power supply unit (PSU) 4 and is connected to the CDU 5 by a
controller cable 6.
[0037] Referring to FIG. 2, the camera 3 has a rear panel 30, which
incorporates the camera interfaces. The rear panel 30 has, among
other interfaces, a power connector 31 for receiving the PSU cable.
This is the main source of power to the camera 3 and also to the
CDU 5, which is connected to a controller connector 32 in the rear
panel 30 by the controller cable 6. In addition to carrying power
from the controller connector 32, the controller cable 6 also
carries video signals to the CDU 5 and button press signals from
the CDU back to the controller connector, as will be described
below. The camera 3 also has a built-in battery (not shown) for the
purposes of retaining information, such as date, time, language of
operation etc., which would otherwise be lost when the camera is
switched off.
[0038] The feature connector cable 8 is connected to the camera 3
by a feature connector 33. In order to save space on the rear panel
30, the feature connector 33 is able to receive a number of
different signals from various peripheral devices.
[0039] Once a video sequence has been recorded, it may be desirable
to download the sequence to a PC or laptop for playback or saving.
For this purpose, a standard RJ-45 Ethernet socket 34 is provided
on the rear panel 30. It will be understood by the skilled reader
that any other suitable form of connection, wired or wireless, such
as FireWire (IEEE1394), USB (universal serial bus), or Bluetooth,
may alternatively be employed.
[0040] The rear panel 30 also has a PCMCIA slot 35 for storing
video data onto a flash memory card. In addition, there is a SVGA
connector 36 for connection to an optional, additional monitor for
viewing purposes. A composite video BNC connector 37, providing
standard PAL or NTSC composite colour video to another, optional
video monitor unit is also provided. The video available from the
connector may be switched between NTSC and PAL via the menu system
in the CDU. Finally, there is a power LED 38 and a fuse 39.
[0041] In order to protect the connectors when the camera 3 is in
use, a protective bar 40 is provided at the base of the rear panel
30. This prevents damage to the connectors, for example, should the
camera 3 be pushed back against a wall when in storage.
[0042] The basic layout of the hardware of the camera 3 of FIG. 2
will now be described, with reference to FIG. 3. The camera 3 has a
CMOS image sensor 300, with a full-frame resolution of just under
0.5 megapixels. The sensor 300 has an active pixel structure
allowing for a synchronous rather than conventional rolling
shutter, such that all pixels in the sensor array receive light for
the same time period. This is essential for high speed operation,
as otherwise motion blur is experienced, due to the pixels not all
being reset at the same time. A serial programming interface allows
a randomly positioned sub-window of the full array to be read out,
in order to increase the frame rate of the camera 3.
[0043] Image data received by the sensor 300 are digitized by the
camera and then stored in its internal circular buffer memory 302,
consisting of SDRAM. Because of the inherent limitation on the
memory capacity of any high-speed digital video camera, only a
pre-defined sampling time may be recorded for any specified frame
size and frame rate. The memory 302 is therefore configured in a
circular buffer, so that, once the memory has been filled for the
first time in a recording sequence, each new image to be stored
replaces the oldest stored image in the memory. This process can
then continue indefinitely, until a desired event has occurred and
the camera receives a signal to stop recording.
[0044] The total number of pixels the image sensor 300 can process
each second is such that, in this embodiment, the camera 3 can
record at a frame rate of 1,000 fps at full-frame resolution for
about 9s. If faster operation is required, the number of pixels per
frame must be reduced. This is achieved by reducing the active area
of the image sensor 300, a process called windowing. There are
three options for windowing: cutting out the vertical edges of the
scene, cutting out the horizontal edges of the scene, or cutting
out both to leave a central `square`. This permits partial-frame
sequencing at rates up to a maximum of 33,000.
[0045] As indicated above, the video sequence stored in the
camera's circular buffer 302 is displayed on the CDU, either as a
recording playback or as real-time video. A camera microprocessor
304 controls the operation of the electronics inside the camera 3,
in response to data received, both from internal and external
sources. From the circular buffer memory 302, the video image data
is processed in a manner known to those skilled in the art. This
includes correction for fixed-pattern noise, video image
enhancement and smoothing, and colour processing.
[0046] The camera 3 generates a video image which is a SVGA image,
timed to match the PC standard. This is an analogue standard, but
has accurate timings because it carries signals which are
reconstructed from a digital data stream. The camera 3 creates a
progressive, scanned 800.times.600 image data in, 3 colour channels
(RGB). The data represent a digital version of the required
analogue image. This digital data stream is used for the CDU 5.
[0047] The video image data derived from the image sensor 300 is
then converted into low-voltage differential signalling (LVDS) by a
converter 306. Data from the converter 306 may then be transferred
to the CDU 5, via the controller connector 32 as a high-speed
serial data stream.
[0048] LVDS has a number of advantages. Data are converted from
parallel to serial, which affords a great reduction in the number
of wires required. Although the data-rate is much increased as a
result, signal integrity is preserved by sending the data
differentially. Electromagnetic interference (EMI) is also reduced,
since the LVDS signal amplitude is only 0.35V. A LVDS link is able
to support cable lengths of up to 10 metres.
[0049] The LVDS converter 306 converts four 7-bit parallel video
data streams, derived from the image sensor 300, plus a 40 MHz
clock signal into four serial data streams, plus the clock signal.
The output data-rate and clock frequency therefore need to be
synthesised at seven times the input rate, which in this embodiment
is 280 Mbit/sec. This is achieved with a phase-locked loop (not
shown) on the LVDS converter chip, incorporating a divide-by-7 in
its feedback loop. The LVDS data are fed to the controller
connector 32 via a number of dual common-mode filters (not shown),
for the purpose of EMI reduction.
[0050] In addition to the video image data transferred to the CDU 5
in this way, the camera also sends graphical overlay data. This
data is produced by a graphics generator and overlay engine 308,
under control of the microprocessor 304 in the camera 3. The
graphical overlay represents the camera functions available for
selection by a user, in the context of use of the camera 3. This
overlay is therefore variable, and depends on the particular
function the camera is performing at any one time. When a user
wishes to select a different function from the one the camera 3 is
performing, the user may send a control signal to the camera. In
the present embodiment, this control signal is in the form of an
RS-232 signal, which is received by a RS-232 receiver chip 310 and
then transmitted to the microprocessor 304. The microprocessor 304
then determines the desired function to be performed and requests
the appropriate video image data from the memory 302, which is
transmitted to the LVDS converter 306 for transfer to the CDU 5,
along with a new graphical overlay, as required by the new camera
function.
[0051] One such function available for selection by a user is the
camera's record mode. In this mode, the camera 3 will store video
image data in its circular buffer memory 302 indefinitely, until a
signal is received by the camera 3 to stop recording. The method of
stopping the camera 3 is highly important as it is this which
determines which part of a video sequence is captured. There are
two methods of stopping the record mode of the camera 3. The first
is a button press in the menu system of the CDU 5, which
immediately stops the recording process, so that the memory 302
contains the video history immediately prior to the button press.
The second method is to use an external electrical trigger signal,
which causes the camera 3 to stop recording after a user-settable
delay. The trigger signal is received by a trigger and timing
module 312 in the camera 3. By permitting the camera to record for
a pre-defined period after the trigger signal, some of the video
sequence stored before the trigger signal, along with some
subsequently recorded video footage, may be preserved in the
memory. In this way, the trigger signal may occur in the middle of
the event of interest and yet the camera may still record the whole
event.
[0052] The delay between the trigger event and the cessation of
recording is controlled by a frame counter, known as the trigger
counter. The duration of this count may be set from anywhere
between 0% and 100% of the total available record time of the
camera's memory.
[0053] The camera 3 has two extensions to the normal trigger
operation described above. These are called Record On Command (ROC)
and Burst Record On Command (BROC). Once recording mode is selected
in the ROC mode, the camera only records video into the memory
while the trigger signal is true (that is, at active low). By
judicious use of the trigger connection (e.g., dextrous use of the
trigger switch 7) the camera 3 may record several short bursts of
video into the memory buffer 302. For the purposes of ROC and BRQC,
the memory is not treated as a circle, but is regarded as being
linear and having a defined start and end. This has the effect that
when the memory 302 is full, no further recording is possible. A
facility is provided through the CDU 5 to erase individual video
bursts from the memory 302, in case of erroneous recording, and a
further facility is provided to erase the entire memory 302. BROC
is an extension of ROC, in that a trigger edge (rather than an
active level) will cause the camera 3 to record video images for a
pre-defined period of time. In this case, the length of time over
which the trigger signal is active is ignored by the trigger and
timing module 312. This function is especially useful for
unattended operation, when several short events are likely to
occur. The burst time is settable in the menu system, using the CDU
5.
[0054] FIG. 3 illustrates a number of other features which will be
familiar to those skilled in the art and which, for the purpose of
conciseness will not, therefore, be described in further
detail.
[0055] Referring now to FIGS. 4A and 4B, the CDU 5 of this
embodiment of the present invention will be described in detail.
The CDU 5 is a hand-held device, for use in displaying video images
and controlling the camera 3. The CDU 5 displays the video images
on a high-resolution, built-in, colour TFT LCD screen 50 and allows
camera functions to be controlled remotely via a graphical user
interface (GUI). The controller cable 6 may be connected to the CDU
5, using the controller connector 52. The CDU 5 takes power and
video from the camera 3 and requires no batteries or further
connections in order to operate. The LCD screen 50 has a native
resolution of 800.times.600 pixels (SVGA) and also requires a frame
refresh rate and pixel rate equal to the optional SVGA video output
from the camera 3. This means that no scaling or format conversion
electronics are required in the CDU 5, thereby greatly reducing
circuit complexity, power consumption and cost. The LCD screen 50
requires 18-bit RGB video (i.e., 6-bits per colour), which is
achieved by dropping the two LSBs (least, significant bits) of each
colour from the digital video signal in the camera 3. This is
carried out in the camera 3, just before the video image data are
converted to analogue signals, for output to an optional SVGA
monitor (not shown).
[0056] Around the bottom and right-hand edges of the LCD screen 50,
there are a plurality of camera control buttons 54, 56. In order to
increase the flexibility of use of the CDU 5, there are seven such
buttons along the bottom edge of the LCD screen 50, each of these
buttons being a `soft key` 54, that is, the function of each soft
key 54 is not fixed. Instead, the function is determined by the
camera microprocessor 304 and indicated by the graphical overlay
above each soft key 54 on the LCD screen 50. The four buttons on
the right-hand side of the CDU 5 are called function keys 56,
having dedicated functions. From top to bottom when viewed in FIG.
4A, these are: text off (that is, graphical overlay off), up, down
(that is, referring to a quantity to be set in the particular
functional context), and back (that is, return to the next highest
menu). The menu system produced by the graphics generator and
overlay engine 308 is designed to correspond to the layout of the
control buttons 54, 56.
[0057] Referring to FIG. 4B, the CDU 5 is equipped with a stand 58,
which may be set to a number of `click-stop` positions. This
permits the CDU 5 to be stood on a flat surface at various angles
or hung from a convenient hook or other support. The stand 58 may
also be folded flat for storage. The back of CDU 5 also has an
adjustable strap 60, which may be used to allow the unit to be
conveniently held with a single hand. In addition, the CDU 5
contains a tripod mounting hole 62, with the industry standard
thread, which is located under the strap 60.
[0058] FIG. 5 shows a schematic block circuit diagram of the CDU 5.
The CDU 5 does not contain any memory for storing video image data,
since all relevant data is stored by the camera 3 and transmitted
to the CDU 5 when required.
[0059] The CDU 5 contains a small microprocessor 500 (such as the
PIC microprocessor, manufactured by Microchip Technology, Inc.).
This microprocessor 500 converts soft key 54 and function key 56
button presses into control signals, using the RS-232 serial
communications protocol, operating at 9600 baud. The momentary
contact closure of a button 54, 56 is encoded into this standard
using the microprocessor 500, clocked at 4 MHz. Each RS-232 control
signal is transmitted to the camera microprocessor 304 by a RS-232
driver 502 in the CDU 5. Each button press produces two bytes of
data: the first informs the camera 3 which device is communicating
with the camera and the second indicates which button has been
pressed.
[0060] For example, if the leftmost soft key 54 on the CDU 5 is
pressed, a "cA<cr>" signal is transmitted to the camera
microprocessor 304. The `c` indicates that the control signal
originates from the CDU 5; the `A` indicates that the leftmost soft
key 54 was pressed; and the `<cr>` is a standard
end-of-command carriage return. In this way, the camera
microprocessor 304 determines what steps to take and which camera
function to perform.
[0061] The LCD screen 50 has its own driver electronics, as will be
understood by the skilled person, and the CDU 5 contains a voltage
inverter 504, to generate the relatively high voltage required to
drive the LCD backlight. The LCD screen 50 is back-lit using two
miniature cold-cathode fluorescent (CCFL) tubes (not shown) These
require about 2 kV as a starting voltage and a few tens of volts in
operation. A resistor (not shown) sets the brightness of the
back-light: the fitted 0 Ohms value gives a maximum, but this value
can be increased up to 10 kOhms, offering progressive dimming,
should this be required.
[0062] As described above, the camera 3 transmits the video image
data to the CDU 5 in the form of LVDS. The video image data and
clock signal transmitted by the camera 3 are at 280 MHz, that is,
seven times the parallel video pixel rate. These signals all go
through the common-mode filters (not shown) in the camera 3, to
prevent high-speed signals generated within the CDU enclosure from
being radiated from the LVDS cable 6. The CDU 5 contains a LVDS
receiver chip 506, which receives the video image data and
interfaces directly with the LCD screen 50, to display the video
images and the graphical overlay. The LVDS receiver chip 506
converts the differential data to single-ended, before recovering
the original parallel video data, synchronising signals and 40 MHz
pixel clock. That is, the LVDS receiver chip 506 in the CDU 5 does
exactly the opposite of the LVDS converter and transmitter 306 in
the camera 3. The receiver chip 506 recovers the 280 MHz clock
signal, divides it down to 40 MHz, deserializes the 4 streams of
data and regenerates exactly what was originally transferred to the
LVDS converter 306.
[0063] The bottom two bits of each colour (R0, R1, G0, G1, B0 and
B1) are discarded by the receiver chip 506, since the LCD screen 50
requires 18-bit, rather than 24-bit, colour data. The LCD screen 50
also requires two further synchronising signals: a 4.0 MHz pixel
clock, and a signal to indicate the active area of the video
displayed. Horizontal and vertical synchronising signals, which are
generated in the camera 3 for the other, optional video outputs,
are not needed by the CDU 5. These are, however, sent over the LVDS
link, being output on the camera's controller connector 32 for the
purposes of future expansion.
[0064] The resulting parallel data, containing a digital replica of
the analogue image, is then driven directly into the LCD screen 50.
The LVDS receiver chip 506 has outputs which are designed to drive
parallel data into LCD panels, so the receiver chip and LCD screen
are connected by a flexible cable (not shown). The LCD screen 50
takes 6 bits from each channel and turns this into an image, as
will be understood by the skilled reader.
[0065] The camera electronics are configured in such a way that the
clock frequency, bus width of the controller connector 32 and
image-timing circuitry of the camera 3 result in the video image
data transfer rate of the camera 3 corresponding to the video image
display rate of the CDU 5. The arrangement of the camera
electronics in this way permit the CDU 5 to be able to display
video images without the need to store them locally. This even
extends to buffering memory, so that video image data transferred
from the camera 3 to the CDU 5 are displayed as video images
substantially immediately upon receipt by the CDU.
[0066] The principle of operation of the CDU 5 will now be
described, with reference to FIGS. 6A and 6B. To navigate through
the menu system, generated as a graphical overlay on the CDU screen
50, the button 54, 56 nearest the desired selection is pressed.
When a camera function has been selected and a parameter is to be
set, the desired value may be chosen by using the up and down
function keys 56, on the right hand side of the screen 50.
Repeatedly pressing these buttons 56, or pressing and holding the
control button, will cycle through the available values. The
current value is displayed on the screen 50, both above the soft
key graphical overlay and adjacent the up/down buttons 56. To
return to a higher menu, the back function key is pressed. If there
is a requirement for a text free screen, the text off function key
is used to cycle the on-screen text, through the full, time/date
only and off options.
[0067] In order to analyse an event, a clear line of sight must be
found for the camera 3. A tripod or magic arm may be required to
hold the camera 3 in place. An appropriate lens 9 is chosen and
fitted to the front of the camera 3. Additional lighting, with its
associated tripods etc., may need to be provided. The camera 3 is
switched on, and directed towards the region of interest. The frame
speed and shutter setting are chosen, using the graphical overlay
menu described above. The lighting and lens 9 are adjusted
appropriately and the camera 3 is then placed in record mode. As
described above, the camera 3 takes video at high frame rates and
stores it in the camera's built-in memory 302. This memory 302 is
configured in a circle so that, once the memory is full, each new
frame replaces the oldest stored frame. In this way, the camera 3
keeps a rolling history of the scene in view, a process which may
continue indefinitely. Once a desired event has occurred, the
camera 3 is stopped or triggered. During the entire set-up and
record process, the CDU 5 and any monitor optionally attached will
display the live image in full colour and in real time. Once the
required video clip is stored in memory 302, it may be viewed by
using the camera's playback function. In this mode, video may be
played forwards or backwards and at a range of speeds. A convenient
bookmark system is also provided for improved navigation between
sections of interest. The memory 302 in the camera 3 will be erased
when the power is switched off, so if it is necessary to preserve
the captured video after power off, it may be recorded onto a
PCMCIA memory card, when this is inserted into the card slot 35
provided. The internal memory 302 is much bigger than any card
currently available, so only a subsection of video may be stored.
However, since high-speed video clips generally contain a large
amount of "dead time" (that is, redundant video footage recorded
before and after the event(s) of interest) and a relatively small
amount of useful motion, the camera 3 has a clip select function.
This function permits a precise selection of the recorded video to
be saved.
[0068] FIG. 6A shows the CDU display screen 50, displaying a `live`
(colour) video image shortly after switch-on of the camera system
1. The CDU display screen 50 is updated at 60 fps at all times, to
the SVGA video signal standard. This is independent of the rate at
which a recorded video sequence is being played back. That is,
regardless of whether the CDU 5 is playing back a still image
(e.g., a single, selected frame from a recorded video sequence) or
a moving image at a fast playback rate, the screen 50 itself will
still be updated 60 times per second.
[0069] FIG. 6B shows the CDU display screen 50, displaying a
recorded frame in the camera's playback mode. As in FIG. 6A, camera
status information is provided by the graphical overlay at the top
of the screen 50 and the camera function options are listed along
the bottom of the screen.
[0070] As described briefly above, the camera 3 of the present
invention is capable of connecting to other devices in a variety of
ways. For example, the camera 3 may be externally triggered or
synchronised, and may also record analogue electrical signals along
with the video.
[0071] A remote-control pad (RCP), incorporating functional keys as
described above may also be used to control the camera 3, although
a separate monitor would then be required. This hand-held unit may
be connected to the camera's controller connector 32 and may be
powered by the camera. The RCP uses a similar circuit for encoding
button presses into RS-232 serial data as the CDU 5. This indicates
to the camera that the device is the RCP by prefixing each data
byte with the character `r`. The camera 3 is then able to recognise
the presence of the RCP and operates a specialised menu system,
which is displayed on a PC monitor or TV monitor. The RCP may then
be used to navigate the menu system. Preferably, however, the
camera 3 is controlled solely with the CDU 5.
[0072] As will be understood, the camera 3 is capable of
interpreting the signals received through each of the interfaces on
the rear panel 30 differently and, where requested, to return data
to the appropriate interface.
[0073] The trigger signal received by the trigger and timing module
312 may be transmitted by one or more trigger switches, one or more
photosensors, or other suitable trigger devices. Alternatively, the
trigger signal may be received from another camera recording the
video sequence, either simultaneously but from a different location
or angle, or at an earlier-stage in the sequence with the trigger
signal indicating that the other camera has run out of memory.
[0074] Although the soft keys 54 and function keys 56 have been
described as control buttons, they may alternatively be switches,
dials, pads, rollers, joysticks and the like. Furthermore, the LCD
screen 50 may additionally or alternatively be a touch-sensitive
screen.
[0075] The above embodiments of the present invention are by way of
example only. Other foreseeable alternatives or equivalents are
also envisaged.
* * * * *